Lycopene is a natural pigment, particularly abundant in tomatoes and watermelon, having intense red color. Due to this characteristic, as well as its safety and beneficial effects, lycopene is widely used in the food industry as a coloring agent, usually in the form of oleoresin, i.e. a suspension in natural lipids. In this form, lycopene oxidation (crystalline lycopene being highly unstable) and bacterial degradation are prevented, most likely due to the lipids and natural antioxidants present. Furthermore, lycopene is used as food supplement thanks to its antioxidative and chemoprotective properties.
Although lycopene can be prepared by synthesis [Karrer et al., Helv. Chim. Acta 33, 1349 (1950); Isler et al., ibid. 39, 463 (1956)], it is usually obtained by extraction from tomatoes (Lycopersicum esculentum). As lycopene has intense red color only when in the crystalline form, the extraction process should allow to obtain the product in this form.
To date, the suggested methods (WO 95/16363 and WO 97/48287) comprise the separation of the serum from the pulp, and the extraction of the latter with solvents. In WO 97/48287 tomatoes, before pulp-serum separation, which has to be performed under controlled conditions, are subjected to heat treatment; the extraction is carried out in the hot as well.
Although these processes may be used with any type of tomatoes, the lycopene starting content should preferably be above 50 ppm.